In order to judge the effectiveness of an advertising campaign for a certain brand of pretzel, a company obtained a simple random sample of 95 convenience store receipts the week before the ad campaign began, and found that 28 of them showed a purchase of the pretzels. Another simple random sample of 65 receipts was taken the week after the ad campaign, and 33 of them showed a pretzel purchase. Construct a 98% confidence interval for the difference between the proportions of customers purchasing pretzels before and after the ad campaign. Interpret the results. A marketing manager claims that the proportion of customers who purchased pretzels did not change after the ad campaign. Does the confidence interval contradict this claim?

In order to judge the effectiveness of an advertising campaign for a certain brand of pretzel, a company obtained a simple random sample of 95 convenience store receipts the week before the ad campaign began, and found that 28 of them showed a purchase of the pretzels. Another simple random sample of 65 receipts was taken the week after the ad campaign, and 33 of them showed a pretzel purchase. Construct a 98% confidence interval for the difference between the proportions of customers purchasing pretzels before and after the ad campaign. Interpret the results. A marketing manager claims that the proportion of customers who purchased pretzels did not change after the ad campaign. Does the confidence interval contradict this claim?

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018

18th Edition

ISBN:9780079039897

Author:Carter

Publisher:Carter

Chapter4: Equations Of Linear Functions

Section: Chapter Questions

Problem 8SGR

See similar textbooks

Similar questions

What is meant by the sample space of an experiment?
During a flu vaccine shortage in the United States, less than a majority of people were able to receive the vaccine. The results of a survey given to a random sample of 2,350 vaccine-eligible people indicated that 978 of the 2,350 people had received flu vaccine. a) Construct and interpret a 95 percent confidence interval for the proportion of vaccine-eligible people who had received flu vaccine.
A research group studying cell phone habits asked the question “Do you ever use your cell phone to make a payment at a convenience store?” to people selected from two random samples of cell phone users. One sample consisted of older adults, ages 35 years and older, and the other sample consisted of younger adults, ages 18 years to 34 years. The proportion of people who answered yes in each sample was used to create a 95 percent confidence interval of (0.097,0.125)(0.097,0.125) to estimate the difference (younger minus older) between the population proportions of people who would answer yes to the question. Which of the following is the best description of what is meant by 95 percent confidence? In repeated random sampling with the same sample size, approximately 95% of the sample proportions from the younger group will be between 0.097 and 0.125 greater than the sample proportion from the older group. A In repeated random sampling with the same sample size,…
A new television series must prove that it has more than 25% of the viewing audience after its initial 13-week run in order to be judged successful. Assume that in a sample of 400 households, 112 were watching the series. (b) Find a 99% confidence interval for the proportion of the viewing audience after its initial 13-week run
In doing market research for the Ford Motor Company, you find that a random sample of 800 households includes 721 in which a vehicle is owned. Based on those results, construct a 98% confidence interval for the percentage of all households in which a vehicle is owned.
In a sports poll, 142 of 500 randomly selected Americans indicated that they consider themselves to be baseball fans. Calculate a 98% confidence interval for the proportion of Americans who consider themselves to be baseball fans.
In a survey of 500 potential jurors, one study found that 350 were regular watchers of at least one crime-scene forensics television series. Assuming that it is reasonable to regard this sample of 500 potential jurors as representative of potential jurors in the United States, use the given information to construct a 95% confidence interval for the true proportion of potential jurors who regularly watch at least one crime-scene investigation series.
in a random sample of 800 austin automobile owners, it was found that 480 would like to see the size of the cars reduced. A 95% confidence interval for the proportion of all austin car owners who would like to see another car is: a) (0.532, 0.667) b) (0.572, 0.628) c) (0.566, 0.634)
Suppose that a safety group surveyed 1,100 drivers. Among those surveyed, 65% said that careless or aggressive driving was the biggest threat on the road, and 25% said that cell phone usage by other drivers was the driving behavior that annoyed them the most. Based on these data and assuming that the sample was a simple random sample, construct and interpret a 95% confidence interval estimate for the true proportion in the population of all drivers who are annoyed by cell phone users. The confidence interval estimate is ??––––––??> (Round to three decimal places as needed. Use ascending order.) Interpret the confidence interval estimate. A. There is a 0.95 probability that the population proportion of drivers who are annoyed by cell phone users is in the interval. B. There is 95% confidence that the population proportion of drivers who are annoyed by cell phone users is in the interval. C. There is 95% confidence that the population proportion…
The St. Lucie County Health Department needs to estimate the proportion of all children in the county aged 19-35 months that are completely up to date with all state-recommended immunizations. The St. Lucie County Health Department found that 67% of a random sample of children in the county aged 19-35 months were completely up to date with all state-recommended immunizations. Find three different confidence intervals - one with sample size 239, one with sample size 596, and one with sample size 937. Assume that 67% of the children each sample are completely up to date with all state recommended immunizations. Notice how the sample size affects the margin of error and the width of the interval. Report confidence interval solutions using interval notation. Report all solutions in percent form, rounded to two decimal places, if necessary. When n=239n=239, the margin of error for a 97% confidence interval is given b When n=239n=239, a 97% confidence interval is given by When n=596n=596,…
The St. Lucie County Health Department needs to estimate the proportion of all children in the county aged 19-35 months that are completely up to date with all state-recommended immunizations. The St. Lucie County Health Department found that 67% of a random sample of children in the county aged 19-35 months were completely up to date with all state-recommended immunizations. Find three different confidence intervals - one with sample size 239, one with sample size 596, and one with sample size 937. Assume that 67% of the children each sample are completely up to date with all state recommended immunizations. Notice how the sample size affects the margin of error and the width of the interval. Report confidence interval solutions using interval notation. Report all solutions in percent form, rounded to two decimal places, if necessary. When n=596n=596, a 97% confidence interval is given by= When n=937n=937, the margin of error for a 97% confidence interval is given by= When n=937n=937,…